MIT Haystack

Statistical Analysis of Solar Geomagnetic Storm Occurrences

Seth Sivak
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     Geomagnetic storms are caused when a solar wind gusts or magnetic clouds impact the Earth's magnetosphere.  The sun produces several different types of disturbances including solar wind (super heated coronal gases from the sun's corona), coronal mass ejecta (large magnetic explosions giving off magnetic clouds), and solar flares (large explosions producing magnetic clouds).  To see a model showing a solar flare produce a coronal mass ejection and a magnetic cloud impact the Earth's magnetosphere click here.  When a group of charged particles (magnetic clouds or solar wind)  collides with the magnetosphere it charges the magnetosphere and produces a geomagnetic storm.  Geomagnetic storms have many effects on Earth.  Geomagnetic storms produce beautiful Auroras, but they also have the capability of disrupting cell phone use, Global Positioning Satellites, taking down power grids and threatening astronauts with harmful radiation.  Geomagnetic storms affect everything that has to use radio waves because all radio waves pass through the ionosphere and that is where the storm impacts.  Auroras (Northern Lights) are seen throughout the world during very large storms, but mainly seen at higher latitudes (Canada and Northern U.S.A.).  The intensity of geomagnetic storms is measured in Kp.  Kp ranges from 0 (no activity) to 9 (extremely high activity) and it is quasi logarithmic, very similar to the Richter Scale for Earthquakes.  Kp is derived 8 times a day (3 Hour intervals) from mid-to-high latitude magnetometer measurements from all over the globe.  Geomagnetic storms typically occur during the solar maximum.  The solar maximum happens about every 11 years.  The level of Solar activity is measured in F10.7 cm x-ray flux

For more information on Solar Activity and Geomagnetic Storms please look at the Links page.

     Our research is done using both of these indices, (Kp and F10.7) and one goal was to find a pattern in geomagnetic storm occurrence.  Another goal of the project was to find out when the best time is to plan radar operations to collect data on geomagnetic storms.  Our concentration was on very large storms (Kp > 8), however we also did a lot of research with all levels of Geomagnetic storms (Kp > 5).  The existing theoretical models and data analysis that we studied throughout the project stated that the maximums are found near the equinoxes (March 22nd and September 22nd).  Also it was believed that March and April are the most active periods of the year.  These ideas became the basis for the research, we wanted to confirm for ourselves that they were correct.
     Using 52 years of Kp and F10.7 X-Ray flux data (1950-2002) from the MIT Millstone Hill Madrigal Database we performed an independent analysis.  There is clearly a maximum at the equinoxes, the larger one being in September.  Also we found a large maximum during July and an interesting diurnal variation.

For more information on our findings visit the Results page.

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Web Page Created 06-03-02